Prius battery replacement experience

I just finished replacing the hybrid battery in my Prius, and wanted to share my experiences.

My first 2005 Prius had finally died after almost 300,000 miles with near-zero problems about a year ago, so I went to a local Toyota dealer and bought another used 2005 Prius. It was overall in good shape for an 11 year old car; the one thing that had worried me was that it had less than 100,000 miles - I thought it hadn't been driven enough to ensure a long battery life. And so it was. Around 130,000 miles, I noticed that the battery went quickly between one red bar and all-full green. Around 144,000 miles, the dashboard lit up like a Christmas tree, and I read codes P0A80 and P3018. It was drivable for another 300 miles or so, but eventually I had to get it towed. Thankfully, diagnosing the problem was trivial; it was a clear-cut case of a dead hybrid battery.

To make matters worse, we live in the middle of nowhere, and the only car repair shop (best mechanic I ever had!) in the area had just closed for good a week earlier. Talk about a perfect storm! The closest trustworthy shop is 50 miles away, the closest Toyota dealership even further.

Anticipating the problem, I had already scoped out various options. The first decision was refurbished or new? Refurbished batteries probably don't have a very long service life, but given the age of the car, it might still be worth doing. I drive a lot, so three years from now it'll easily have at least 250,000 miles. Most refurbishers seem to be fly-by-night operations, of course.

My first contact was with battery4hybrid.com. Has been in business for almost 10 years, and several locations nationwide, so it seemed like a safer choice than most. The price was decent, and what clinched the deal was that they make house calls to install the battery. I called, and the tech was supposed to show up the next day. Alas, he called at the last minute to cancel, and promised he'd come out next day or day after. No such luck. I'm only thankful that this company flaked out on me BEFORE I spent money.

Plan B was to get a battery from Toyota and do the job myself. Turns out that is not as easy as it sounds. Even though the price of the battery is reasonable ($2500), thanks to the core deposit I'd have to come up with $4000. On top of that, it would take a week to get shipped, and the battery comes with only one year of warranty.

Plan C was to order a battery from Dorman. A very well established company, and I frequently buy Dorman parts for all my cars. I went to my local car part store and asked if they could order it. They could, and in fact had one in the area, ready to be trucked to the store within 24 hours. A very good price ($1400 plus core deposit), and 3 years of warranty, unlimited mileage, vs. Toyota's one year.

The battery came in a very sturdy crate, bolted down (seems that some refurbishers don't package the batteries well, causing the battery to be bent out of shape).

Installation of the battery proved to be almost trivially easy (if you know what you are doing and are comfortable with the high voltage). The battery was ever so slightly misshapen so some of the bolts didn't fit perfectly, but it was only a few millimeters off and easily corrected.

I just completed a 30 mile test drive. All codes are gone, the battery charges and discharges just as it should, mostly staying in the blue range, rarely ever going red or green.

I am a happy camper. Of course, I still expect more problems with a car this age, but Prius seems to be overall a very reliable car.

 

The Dorman battery was plug and play. Two parts had to be transferred from the old to the new battery. One was the orange safety disconnect. The other was the little spring-like piece of metal that covers the 200-V cables going to the battery. There is a video on the Dorman site that explains which piece I'm talking about. Of course, all the bolts also have to be reused.

There are a few things that are slightly tricky. Lifting the battery does require a second person. No matter how strong you are, don't even think about doing it on your own. The reason you need a second person isn't actually the weight itself, but rather because you have to carefully maneuver the battery around a wiring harness in the floor of the car that can't be removed. Also, the case of the battery is very soft metal, and you have to be careful not to bend it, especially the cooling channel at the bottom. Basically, make sure no part of the battery ever carries weight, except for the lip that the bolt holes are in.

Protective gloves are a good idea due to sharp metal edges. If you are careful, you can do it without gloves.

Dorman recommends the high-voltage gloves at two points in the process. The first is when removing the safety disconnect plug. I suspect that it is a good idea if the battery has been physically damaged, just in case the battery case carries 200V. Under normal circumstances, it should be safe to touch the safety disconnect unprotected, though.

The second time is after taking off the cover for the controller and the various connectors. This exposes the bare metal of the high-voltage cables. The first thing you need to do at that point is, with a voltmeter, test the voltage across the battery connectors; it is supposed to have 0V voltage (due to the safety disconnect). Dorman says "less than 30V". Personally, I'd say if there is any voltage at all, you may want to stop and investigate, and/or call an expert.

Since you don't know yet if the battery is de-energized correctly, wearing high-voltage gloves is a good idea here, too. That said, both situations are really judgment calls. If the battery is not physically damaged, and your voltmeter probes are long enough, and you feel comfortable working potentially near high voltage without touching anything dangerous, you might get away without using high voltage gloves. All in all, the precautions are similar to what you'd have to do to work on your house 120V wiring.

If the battery simply died to old age, and isn't leaking, you are probably OK without the gloves. If the car was in an accident, or the safety disconnect breaks in the battery, or something else goes wrong, then you may want to be more careful.

A few other things that were slightly tricky: cleaning the cooling fan. Eventually, a combination of a computer vacuum, a toothbrush, a shop vac, and a pipe cleaner did the trick. I found it easier to remove the fan from the car for the cleaning.

Also, I washed out the duct work, including the two filters, with a garden hose. Be careful, there is a sensor in one of the pieces of ducting that you probably shouldn't get too wet.

Also, when attaching the battery to the car, or the various covers to the battery, be careful - the soft battery case can bend easily - and once it does, it can be hard to screw the bolts in correctly.

All in all, though, I'd say the process is no harder than installing a car stereo, as long as you are comfortable with the 200V and with the weight.

The return process was simple. I simply put the bad battery back into the same crate the new one came in, bolted it down, strapped it down, etc. and hauled it down to the car part store. They handled the core return.

And the battery is still working beautifully. It remains to be seen how long this one lasts.

 

Time for an update... I drove the Prius for about 1500 miles after installing the replacement battery. At first, I didn't notice much change to the mileage, but it did get better over time - I suspect that one of the controller had to recalibrate for the new battery. I now notice far more of the "50 kwh energy recovered" symbols pop up on my display. So all is good, right?

Unfortunately, no. Just past the 1500 mile point, the dashboard lit up like a Christmas tree and the car would not move; I had to get it towed to the nearest Toyota dealer (which thankfully was only two miles away). My OBD II reader did not read any codes this time, but the dealer read code P0AA6 with subcode 602 (High Voltage leak in the battery case), and also confirmed that there was no installation issue. Apparently, there was a manufacturing defect in that particular battery, probably not related to any cells, just a plain old mistake.

The good news is that the manufacturer honored the warranty with no problem. It was just a matter of getting the logistics worked out to get the battery to the dealer. And of course I was responsible for the labor.

One thing that surprised me is that Toyota's flat rate labor is 5 hours - and it took me five hours to replace the battery. I would have thought that as an inexperienced newbie like me would take much longer than a Toyota mechanic, but apparently not. Maybe it is because most of the time is spent disassembling trim pieces.

Let's just hope that the second new battery will last the lifetime of the car!

With 20/20 hindsight, would I do anything differently? Very little, actually. Buying a battery from Toyota would have made the warranty logistics dramatically easier, but financially I still came out ahead even after paying the Toyota dealer to replace the battery. In any case, for the original replacement, going to the dealer wasn't really an option; there was no Toyota dealership anywhere nearby.

 

Here is the process: I first talked to Dorman. They asked for OBD code and sub-code (which I had to get from the Toyota dealer), and then issued a warranty authorization ID. With that number in hand, I went to the car parts store that sold me the battery. Fortunately, it was a chain, and just as fortunately, they had a location a few blocks from the Toyota dealership (the location where I originally bought the battery was 50 miles away). For the store manager, dealing with this issue was a first, he had to research how to place the order and process the return. But he got it done very well, professionally and quickly.

They had several of these hybrid batteries in stock (in the distribution warehouse); I placed the warranty order around noon, and the battery arrived at the store that same night. It did *not* come from Dorman directly, but rather from a Southern California distribution warehouse. The store delivered the battery to the Toyota dealer, who swapped it out. Toyota gave me zero problems about using a third-party battery, but that was probably because my car already had a third-party battery installed. All in all, everybody involved, at the Toyota dealership, at the car part store, and at Dorman, was nothing but professional, helpful and courteous. The inconvenience and expense aside, the overall experience was a nothing but positive.

I was also lucky that I had the time to coordinate everything.